Friday, October 19, 2012

Lenovo x220t Tablet and the broken Wacom 0xE6 tablet

I noticed that my tablet didn't work anymore. In fact, the tablet itself didn't even show up in /proc/bus/input/devices. At first I suspected a kernel bug and rebooted into a variety of different Fedora kernels, but to no avail.

Wacom's vendor ID is 056a, but the tablet in the x220 is a 0xE6, not a 0x94 (the latter of which doesn't exist). With that info, googling for a solution was a bit easier. As suggested in the thread on linuxwacom-devel a power off did indeed fix the issue for me.

It turns out this is an issue with kernel 3.5.3 and 3.5.4, but it is fixed in 3.5.5. kernel bug. As Ping states:

The root cause is somewhere in the kernel tablet is set to a wrong
mode. Once it is in that mode, a reboot won't reset it to normal. We
have to power it off and wait a few seconds for all bits to reset.
That's why I tell people to even unplug the power cable since bits may
stay as long as they get power.